Fastest eater. Probably Kakashi, i remember watching an episode about them trying to find out his face, they give him a bowl ramen and he finishes it in less than a second.
However, for people who can eat the most its probably Allen Walker

I have to agree that Kakashi from Naruto eats the fastest.. He can finish a bowl of a ramen in a blink of an eye while being observed by the prying eyes of 3 ninjas. While that episode is nothing more than a filler, it is still part of the Naruto anime.

The biggest eater I've seen so far is Goku. He can eat something as big as a dinosaur.